1. Scope of Invention
This invention relates generally to systems for coating objects by vacuum deposition, and more particularly to such a system having a uniquely configured plasma producing gun and protective vapor deposited coating arrangement.
2. Prior Art
Vacuum deposition of vaporized metal and plasma-energized protective coatings onto the exterior and interior surfaces of objects such as plastic components for automobile manufacturers which require a high degree of uniformity and finish quality are well known. One major manufacturer of such equipment is F. J. Stokes Corporation.
These prior art vacuum deposition systems typically include a medium to large sized vacuum chamber, a large moveable rack or carriage for holding and supporting a plurality of objects for coating within the chamber, means for conveniently moving the loaded object support carriage into and out of the chamber, an arrangement for producing vaporized metal for depositing a first metallic layer of vaporized metal onto the surface of the objects and a source of vaporized protective liquid such as a monomer which is applied atop the vaporized metal first deposited onto the surfaces of the objects within the vacuum chamber.
The use of a plasma created within the vacuum chamber in the vicinity of the metal coated objects is also typically utilized to energize the vaporized liquid monomer and to accelerate the liquid monomer within the vacuum chamber to facilitate a uniform protective coating applied to the objects.
A shortcoming with respect to the plasma coating technique for energizing and applying the liquid monomer is with respect to the placement of the discharge or spray bar utilized to disperse the vaporized monomer into the vacuum chamber. Typically, the monomer discharge is within a lower portion of the vacuum chamber while the plasma source is positioned in another location within the vacuum chamber whereby the vaporized liquid monomer entering the vacuum chamber must first be drawn toward the plasma and then energized and dispersed throughout the vacuum chamber. This arrangement leads to premature, undercured and non-uniform deposition of the liquid monomer onto the metal coated surfaces of the objects before being fully energized by the plasma condition created for that purpose within the vacuum chamber.
Applicant is aware of a number of patented prior art systems which are listed below which typically represent the state of the art in vacuum deposition.
______________________________________ 3,086,889 Strong 3,097,113 Welsh 3,117,887 Shepard, et al. 3,518,108 Heiss, Jr., et al. 3,524,426 Ogle, et al. 3,641,973 Shrader 3,713,869 Geffeken, et al. 3,970,820 Mahl 4,173,944 Koppl, et al. 4,338,883 Mahler 4,447,374 Tanaka 4,478,174 Ranger 4,673,588 Bringmann, et al. 4,687,679 Beale 4,863,756 Hartig, et al. 5,053,243 Schuurmans, et al. 5,182,000 Antonelli, et al. 5,217,749 Denton, et al. 5,312,529 Antonelli, et al. 5,340,628 Tanisaki, et al. 5,401,541 Hodnett, III 5,538,909 Poliquin, et al. 5,560,963 Tisack ______________________________________
However, for the most part, these prior art references are of limited scope and of a specialty nature, some of which utilize metal vaporizing boats for vacuum deposition of a metallic film. A portion of these references also do not depend upon or require the plasma atmosphere within the vacuum chamber in a fashion similar to that of the present invention.